https://gitlab.synchro.net/main/sbbs/-/commit/15e40a45a990d2a6d786ef22
Modified Files:
	src/sbbs3/getnode.cpp
Log Message:
Fix potential deadlock in getnodedat(), observed on macOS

Upon any node.dab lock or read failure, this code would cause errormsg() which
would often/usually end up claling getnodedat() which would block forever trying
to acquire the ndoefile_mutex (introduced in commit b9633069, I'm not clear why).

Unlock/release the mutex *before* calling errormsg().
--- SBBSecho 3.23-Linux